1. Field of the Invention
The present invention relates to an etching method for processing a substrate and a dry etching method for a polyetheramide resin layer. More specifically, the present invention relates to a silicon-anisotropic etching method used in micro-machining techniques such as formation of an ink supply port in an ink-jet head or a pressure sensor, or to a dry etching method suitable for etching a protective film as an ink-resistant layer in an ink-jet printing head or a protective film of a semiconductor device.
2. Description of the Prior Art
As an etching method used in micro-machining, a chemical etching technology based on a photolithography is presently a mainstream technology. A silicon (herein after, also called xe2x80x9cSixe2x80x9d simply) substrate (wafer) having a surface whose crystal plane orientation is of  less than 100 greater than  plane, or of  less than 110 greater than  plane is generally used as a substrate subjected to the above-stated chemical etching. Employing the Si substrate having such plane orientations for performing an alkaline chemical etching to that substrate causes selectivity with respect to etching progression to be shown in respective depth (dig-in) and width (spread) directions, thereby, an anisotropy of etching can be obtained. For example, this anisotropy of etching allows a hole having a large depth and a small width to be formed. Further, in the case of employing the substrate having the crystal plane orientation of  less than 100 greater than  plane for etching, the etching progression in the depth direction can be controlled because geometry in the depth direction is determined depending on an etching width. For example, a hole having a configuration, which becomes narrower in the depth direction at an angle of 54.7xc2x0 from an etching starting plane can be obtained. Therefore, careful determining of a substrate thickness and an etching width allows a control of the formation of a hole which elongates halfway in the substrate thickness to be performed positively and easily without causing the hole to pass through the substrate (see FIG. 4).
It has been well known that the above-described etching characteristic is applied in micro-machining techniques such as production of an ink-jet head, a pressure sensor and the like.
A chemical etching employing an alkaline etching solution is performed by generally using strong alkali solution for an extended etching time and heat treatment is also performed during the etching. Considering such etching conditions, a dielectric film such as SiO2, SiN or the like is generally used as an etching-resistant mask.
However, since these films are generally formed as deposition films made by sputtering or CVD, it is difficult to form these films without defects, which defective part (pinhole) may lead to a malfunction in the head or the like. Further, machining is becoming finer in structure year by year, small defects become what can not be disregarded.
As described above, in the micro-machining technology such as the head production, it is a strong demand to form a defectless etching mask.
The object of the present invention is to provide an etching method capable of using a mask material which has an alkali resistance and does not generate defects such as pinholes and performing reliable etching, a production method of an ink-jet printing head using the above method, an ink-jet head and an ink-jet printing apparatus.
In the first aspect of the present invention, there is provided an etching method in which an etching-resistant mask having a predetermined opening pattern is provided on a substrate and etching is performed through said etching-resistant mask so as to process said substrate,
wherein a polyetheramide resin layer is used as said etching-resistant mask.
In the second aspect of the present invention, there is provided a dry etching method for a polyetheramide resin layer, wherein said polyetheramide resin layer is etched by means of an etching gas containing oxygen as a main component.
In the third aspect of the present invention, there is provided a dry etching method for a polyetheramide resin layer, wherein said polyetheramide resin layer is etched by means of an etching gas containing oxygen and carbon tetrafluoride as main components.
In the fourth aspect of the present invention, there is provided a production method of producing an ink-jet head for ejecting an ink, comprising the steps of:
preparing a substrate for constructing said ink-jet head;
forming a mask pattern including a polyetheramide resin layer on a surface of said substrate; and
performing etching with use of said mask pattern as a mask.
In the fifth method of producing an ink-jet head for ejecting an ink, comprising the steps of:
preparing a substrate for constructing said ink-jet head;
forming a mask pattern including a two-layered structure of a polyetheramide resin layer formed on a dielectric layer, said two layered structure being formed on a surface of said substrate; and
performing etching with use of said mask pattern as a mask.
In the sixth aspect of the present invention, there is provided an ink-jet head for ejecting ink, said ink-jet head being produced by a production method comprising the steps of:
preparing a substrate for constructing the ink-jet head;
forming a mask pattern including a polyetheramide resin layer on a surface of said substrate; and
performing etching with use of said mask pattern as a mask.
In the seventh aspect of the present invention, there is provided an ink-jet head for ejecting ink, said ink-jet head being produced by a production method comprising the steps of:
preparing a substrate for constructing the ink-jet head;
forming a mask pattern including a two-layered structure in which a polyetheramide layer is formed on a dielectric layer; and
performing etching with use of said mask pattern as a mask.
A polyether amide resin used in the present invention is a material which has a high strength and flexibility to have a high absorbing effect to an external stress, has high chemical resistance not to be affected by acids, alkalis, aromatic solvents and the like, and has high heat resistance and high moisture resistance to be dissolved in a polar solvent to become a varnish which form a film at relatively low temperature at which a solvent only evaporates. Therefore, a layer made with the polyether amide resin can be used as a mask for etching a substrate constructing an ink-jet head to reduce defects such as pinholes generated in the mask during formation of the mask.
In the present invention, a two-layered structure in which the polyetheramide layer is formed on a dielectric layer can be employed to allow the above defects to be reduced and etching with a good accuracy to be performed in, for example, an anisotropic etching.
Further, since the polyetheramide resin has not a photosensitivity by itself, a dispenser or a screen-printing is used in general when performing patterning on the resin. Therefore, the polyetheramide resin has been used in applications which do not require fine patterning, such as a moisture-proof coating for electronic parts, but has been difficult to be used in an application which require the fine patterning, such as an etching mask used in the micro machining technique or a protective film or the like as an ink-resistant layer in an ink-jet printing head. If an attempt is made to employ a method of coating the polyetheramide resin with an etching mask and of dissolving an unnecessary part of the mask, an appropriate masking material has not been available which has resistance to a solvent that can dissolve the polyetheramide resin. However, the dry etching method for the polyetheramide resin layer according to the present invention allows such fine patterning so that the polyetheramide resin layer can be used for a protective film or the like as an ink-resistant layer in the ink-jet printing head in which the fine patterning is required for the protective film.
The above and other objects, effects, features and advantages of the present invention will become more apparent from the following description of embodiments thereof taken in conjunction with the accompanying drawings.